fix(domain,application,infrastructure,app-tauri,frontend): conversation_id redevient un pivot logique IdeA/log/handoff, reprise provider réservée à la sélection explicite — lifecycle: LaunchAgentInput::conversation_id documenté comme sélection explicite (Some = reprise native si disponible sinon handoff portable, None = conversation provider neuve), plus de copie implicite du pivot logique de la leaf au reboot ; fallback silencieux: provider_resume_fallback résolu via resolve_handoff et câblé jusqu'aux adaptateurs Claude/Codex/OpenCode via AgentSessionFactory::create resume_fallback_preamble + with_resume_fallback_preamble — le préambule reste dormant si la session native répond et n'est injecté que si la session provider s'avère introuvable/périmée (fake stale-then-fresh en test, relance fraîche sans erreur utilisateur) ; app-tauri launch_agent: contrat documenté, l'activation ordinaire d'une cellule doit envoyer None même si la leaf conserve un pivot logique d'avant reboot ; frontend CustomAgentChatView: freshOnOpen réinitialise l'état conversation complet (scrollback, view state, conversationId publié, bannière reprise, pagination historique) quand le runtime structuré n'existe plus au remontage — pas de fausse « Conversation reprise » après reboot ; tests: structured_launch_d3 étendu, structured_session_d0, agent_lifecycle structured, CustomAgentChatView freshOnOpen — #372 (QA verte: cargo check --tests -p domain -p application -p infrastructure, cargo test -p application --test structured_launch_d3, cargo test -p domain --test structured_session_d0, cargo test -p application --test agent_lifecycle structured, npm test -- CustomAgentChatView, npm run typecheck, git diff --check ; fichiers .ideai/* et scripts/ hors périmètre ; aucun push)

frontend/src/features/agents/CustomAgentChatView.test.tsx

@@ -6751,6 +6751,79 @@ describe("CustomAgentChatView", () => {
     ));
   });
 
+  it("starts fresh after reboot when both persisted session and conversation are stale (#372)", async () => {
+    const conversation = {
+      readPage: vi.fn(),
+    };
+    const agent = {
+      launchAgentChat: vi.fn(async () => ({
+        sessionId: "fresh-session",
+        assignedConversationId: "fresh-conversation",
+      })),
+      reattachAgentChat: vi.fn()
+        .mockRejectedValueOnce({ code: "NOT_FOUND", message: "session not found" })
+        .mockRejectedValueOnce({ code: "NOT_FOUND", message: "session not found" })
+        .mockResolvedValueOnce({ sessionId: "fresh-session", scrollback: [] }),
+      sendAgentChat: vi.fn(async () => {}),
+      cancelAgentChat: vi.fn(async () => ({
+        sessionId: "fresh-session",
+        outcome: "cancelled" as const,
+      })),
+      closeAgentChat: vi.fn(async () => {}),
+    };
+    const onSessionId = vi.fn();
+    const onConversationId = vi.fn();
+
+    render(
+      <DIProvider gateways={{
+        agent,
+        conversation,
+        system: { pickFile: vi.fn(async () => null) },
+      } as unknown as Gateways}>
+        <CustomAgentChatView
+          freshOnOpen
+          projectId="project-1"
+          agentId="agent-1"
+          agentName="Worker"
+          profile={profile}
+          cwd="/repo"
+          nodeId="node-1"
+          sessionId="stale-session"
+          conversationId="stale-conversation"
+          onSessionId={onSessionId}
+          onConversationId={onConversationId}
+        />
+      </DIProvider>,
+    );
+
+    await waitFor(() => expect(agent.launchAgentChat).toHaveBeenCalledTimes(1));
+    expect(agent.launchAgentChat).toHaveBeenCalledWith("project-1", "agent-1", {
+      cwd: "/repo",
+      rows: 24,
+      cols: 80,
+      conversationId: undefined,
+      freshStart: true,
+      nodeId: "node-1",
+    });
+    expect(conversation.readPage).not.toHaveBeenCalled();
+    expect(screen.queryByText("Conversation reprise")).toBeNull();
+    expect(screen.queryByText("session not found")).toBeNull();
+    expect(await screen.findByText("Nouvelle conversation")).toBeTruthy();
+    expect(onSessionId).toHaveBeenCalledWith(null);
+    expect(onConversationId).toHaveBeenCalledWith(null);
+    expect(onConversationId).toHaveBeenCalledWith("fresh-conversation");
+    fireEvent.change(screen.getByRole("textbox"), { target: { value: "Ready now" } });
+    await waitFor(() =>
+      expect(screen.getByRole("button", { name: "Envoyer" }).hasAttribute("disabled")).toBe(false),
+    );
+    fireEvent.click(screen.getByRole("button", { name: "Envoyer" }));
+    await waitFor(() => expect(agent.sendAgentChat).toHaveBeenCalledWith(
+      "fresh-session",
+      "Ready now",
+      expect.any(Function),
+    ));
+  });
+
   it("uses /clean for a new conversation and disables conversation changes during a turn", async () => {
     let finishSend: (() => void) | undefined;
     const agent = {

frontend/src/features/agents/CustomAgentChatView.tsx

@@ -2238,6 +2238,20 @@ export function CustomAgentChatView({
               setExternalSessionId(null);
               setLiveSessionAttached(false);
               publishSessionId(null);
+              if (freshOnOpen) {
+                // After an application reboot, the leaf can still contain both
+                // ids even though the structured runtime no longer exists. A
+                // normal cell opening must not turn that stale runtime pivot
+                // into an implicit conversation resume (#372).
+                scrollbackChunkCountRef.current = 0;
+                applyChatViewState(emptyChatViewState());
+                publishConversationId(null);
+                setSavedConversationLoadState("idle");
+                setResumedConversation(false);
+                setHistoryHasMore(false);
+                setHistoryNextAnchor(undefined);
+                setHistoryError(null);
+              }
             }
             console.debug("[ticket149] openOrAttach:reattach-existing:not-found", {
               timestamp: new Date().toISOString(),
@@ -2397,6 +2411,7 @@ export function CustomAgentChatView({
     reattachStructuredSession,
     recoverStructuredSession,
     publishSessionId,
+    publishConversationId,
     applyChatViewState,
     conversation,
     agent,